2 Answers
2

If the machine firewall is rejecting ICMP, it is probably also rejecting all other forms of not already authorized access so if opening the firewall to accept ICMP is not an option, you may try the alternative ways below:

If you have access to the router, you can check if the machine is in the connected devices.

If the machine is sharing "Public Documents" you can check if they are available in the network.

If the machine is sharing a printer, you can check the print queue.

Another way but I'm not sure if it will work from a windows machine but issuing the ping on a Linux machine, if the remote windows machine is not connected (offline), the ping command returns "host unreachable" and if it is on and not answering to ping, there is no response.

Is the machine you are talking about is in your own network, or in a network u can reach, then you can try capturing the packets in the network, and from MAC address or from IP address you can know whether the machine is alive or not.
Try WIRESHARK for packet capturing keeping your network card in promiscuous mode.